The invention relates to novel brighteners, a process for their preparation and their use for brightening substrates.
DE-A-2 335 570 discloses stilbene brighteners whose terminal triazinyl radicals are substituted with short-chain polyether alcohols.
EP-A-24 380 discloses stilbene brighteners whose terminal triazinyl radicals are substituted with phenyl-saturated ethylene oxide units.
Surprisingly, there have now been found optical brighteners conforming to the formula (I) 
where
Z is SO3M, COOR1, CONR1, SO2NHR1, NHCOR1, COR2 or CN, where
R1 is M or C1-C3-alkyl and
R2 is C1-C3-alkyl or phenyl,
X is O or NR3, where
R3 is hydrogen or C1-C4-alkyl,
Y is hydrogen or C1-C4-alkyl, especially methyl,
M is hydrogen, an alkali metal cation or an optionally substituted ammonium ion,
n is from 4 to 35, especially from 5 to 25, preferably from 7 to 25 and
m is 0, 1 or 2.
The index n is herein to be understood as a statistical variable and preferably represents the mean.
Preferred brighteners are those in which the radical of the formula 
is derived from compounds of the formula (V) 
Preferred compounds of the formula (V) are phenol, phenolsulfonic acid, aniline, sulfanilic acid, dimetanilic acid (2,5-disulfoaniline).
Preferred brighteners of the formula (I) are those where
Z is SO3M,
m is 0, 1 or 2
X is NH,
n is from 4 to 15, especially from 5 to 15, preferably from 7 to 15,
Y is hydrogen and
M is hydrogen, Na, K or a C1-C4-mono-, -di-, -tri- or -tetra-alkanolammonium.
Particularly preferred brighteners of the formula (I) are those where
Z is SO3M,
m is 1,
X is NH,
n is from 4 to 15, especially from 5 to 15, preferably from 7 to 15,
Y is hydrogen and
M is Na or K.
Particularly preferred brighteners of the formula (I) conform to the formula (II) 
where
M is hydrogen, Na or K and
n is from 4 to 15, preferably from 5 to 15, especially from 7 to 15.
The invention further provides a process for preparing the compounds of the formula (I), which is characterized in that compounds of the formula (III) 
where
A is Cl or F, especially Cl,
are reacted with polyglycols or polyglycol ethers of the general formulae (IV)
Yxe2x80x94Oxe2x80x94[CH2CH2Oxe2x80x94]xe2x80x94nHxe2x80x83xe2x80x83(IV)
where Z, X, Y, m and n are each as defined above.
In a particular embodiment of the process according to the invention, the reaction is effected at a temperature of 20 to 100xc2x0 C., preferably in the presence of an acid-binding agent, such as for example sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate.
The reaction is generally carried out similarly to the procedure disclosed in DE-2 335 570.
Compounds of the formula (III) are known for example from EP-A-860 437.
Preferred compounds of the formula (IV) are for example polyethylene glycols, especially those where n=4 to 35, especially 4 to 25, preferably 5 to 25, particularly preferably 7 to 25, preferably with an average molecular weight of 200 to 1000 g/mol, especially 200, 300, 400, 600 and 1000 g/mol, and also their corresponding monomethyl ethers.
Particular preference is given to using compounds of the formula (IV) which are polyethylene glycols having average molecular weights of 200 to 600 g/mol.
The compounds of the formula (I) according to the invention are generally prepared using an excess of compounds of the formula (IV). The molar excess of IV, based on III, is preferably 5 to 20 mol. This excess of (IV) can be removed from the end product by diafiltration for example. Preferably, however, the excess stays in the end product, since it has a positive influence on the stability of the liquid formulation and also on the whiteness of the brightened material.
The invention also provides brightener preparations containing the brightener of the formula (I) according to the invention and a polyglycol ether. Preferred polyglycol ethers are those of the formula (IV) where the meanings for Y and n can be independent of those of the formula (I).
Preference is given to those brightener preparations containing
10-25% by weight of brightener of the formula (I)
20-60% by weight of polyglycol ether
15-70% by weight of water.
Salts may be present in addition.
When polyglycol ethers of the formula (IV) are used, polyethylene glycols (PEGs) having molecular weights of 1500 to 6000 g/mol can be used in addition. The latter can be present at 0 to 40% by weight, based on the preparation.
The compounds of the general formula (I) according to the invention are optical brighteners for various substrates. Particularly preferred substrates are those composed of natural cellulose such as cotton, paper and wood materials in fine dispersion or materials composed of regenerated cellulose, of wool or synthetic polyamides. The materials to be optically brightened can be present in a wide variety of processing stages such as raw material, intermediate article or finished article and in a wide variety of processing forms such as for example fibers, threads, wovens, formed-loop knits, webs and also films etc.
The compounds according to the invention can also have laundry detergent added to them. The solid and liquid laundry detergents used can contain the customary ingredients corresponding to the prior art.
The compounds of the invention can further be applied during the resin finishing of fiber materials in conjunction with synthetic resins and synthetic resin precondensates. The crosslinking of the synthetic resins can be carried out over a wide pH range, especially from pH 1 to pH 10, in a conventional manner. Thus, especially the compounds of the formula (I) according to the invention in which
Z is SO3M,
m is 1 or 2,
X is NH,
n is from 4 to 15, preferably from 5 to 15, especially from 7 to 15,
Y is hydrogen and
M is Na or K
are suitable for the optical brightening of cellulose materials from acidic crosslinking baths, as is customary for the wash and wear finishing of cellulose fibers.
The compounds according to the invention can further be used for raising the sun protection factor of textile materials. The use of diaminestilbenedisulfonic acid derivatives for raising the sun protection factor of textile materials is known and described for example in EP-A 728 749 ({circumflex over (=)}GB 9 503 474). Suitable for this use are in particular the compounds of the general formula (I) according to the invention where
Z represents COOR1, where R1 is C1-C3-alkyl or M, or represents CONR1, SO2NHR1, NHCOR1, COxe2x80x94R3, where R3 is C1-C3-alkyl or phenyl, or represents CN,
m represents 1,
X represents NH,
n represents from 4 to 15, preferably from 5 to 15,especially from 7 to 15,
Y represents hydrogen or methyl,
M represents hydrogen, an alkali metal cation or an optionally substituted ammonium ion.
To raise the sun protection factor of textile materials, the textile material can be treated directly with the compounds of the invention, or else the effect is achieved as part of a normal domestic laundering process when the laundry detergent used contains the compound according to the invention.
The brighteners of the formula (I) according to the invention are suitable for brightening paper materials in papermaking, for example cellulose, chemical and mechanical pulp, and for brightening the coating compositions customarily used in the paper industry, specifically for brightening unpigmented but especially pigmented paper materials and coating compositions.
The binders in known coating compositions include polymer dispersions based on copolymers of butadiene-styrene, acrylonitrile-butadiene-styrene, acrylic esters, ethylene-vinyl chloride or ethylene-vinyl acetate or based on homopolymers, such as polyvinyl chloride, polyvinylidene chloride, polyethylene, polyvinyl acetate or polyurethanes. A preferred binder consists of styrene-butyl acrylate or styrene butadiene-acrylic acid interpolymers. Further polymer latices are described, for example, in U.S. Pat. No. 3,265,654.
The coating compositions are customarily pigmented using aluminum silicates, such as china clay and kaolin, also barium sulfate, satin white, titanium dioxide or calcium carbonate (chalk).
The coating compositions according to the invention preferably contain 5 to 70% by weight of a white pigment. The binder is preferably used in an amount such that the solids content of polymeric compound comprises 1 to 30% by weight, preferably 5 to 25% by weight, of the white pigment. The amount of the brightener according to the invention is determined in such a way that the brightener is present in amounts of 0.005 to 1% by weight, especially 0.01 to 0.55% by weight, based on white pigment.
The coating composition according to the invention can be prepared by mixing the components in any order at temperatures of 10 to 100xc2x0 C., preferably 20 to 80xc2x0 C. The components also include the customary auxiliaries which can be used to regulate the rheological properties, such as the viscosity or water retention capability, of the coating compositions. Such auxiliaries are for example natural binders, such as starch, casein, protein or gelatin, cellulose ethers, such as carboxyalkylcellulose or hydroxyalkylcellulose, alginic acid, alginates, polyethylene oxide or polyethylene oxide alkyl ethers, interpolymers of ethylene oxide and propylene oxide, polyvinyl alcohol, polyvinylpyrrolidone, water-soluble condensation products of formaldehyde with urea or melamine, polyphosphates or polyacrylic acid salts.
The brighteners of the formula (I) according to the invention are incorporated either into the finished coating composition or into one of the components of the coating composition.
The coating composition according to the invention can be used for coating paper, wood, films, such as for example cellulose, cellulose triacetate, textile materials, etc. Particular preference is given to the application to paper and cardboard and also photopapers.
The coating composition can be applied to the substrate by any conventional method, for example using an air knife, a coating blade, a brush, a roll, a doctor or a rod, and the coating is then dried, for example using an infrared dryer and/or hot air dryer, at substrate surface temperatures in the range from 70 to 200xc2x0 C., preferably from 90 to 130xc2x0 C., to a residual moisture content of 3 to 6% by weight.
The coating compositions according to the invention provide coatings notable for an optimum distribution of the optical brighteners across the entire surface and an attendant increase in the whiteness and also for a high lightfastness.